The present invention relates to an apparatus for removal of water or other liquids and concentration of a substance, and more particularly to a vacuum centrifugal concentrator, and still more particularly to a vacuum centrifugal concentrator that heats the substance being processed to enhance the concentration procedure.
The use of vacuum centrifugal concentrators for removing moisture from a liquid substance to provide a dry specimen for analysis is well known. Such a device is fully disclosed in U.S. Pat. No. 4,226,669, the disclosure of which is herein incorporated by reference for background material. However, the effective use of heat with vacuum centrifugal concentrators to enhance the drying process and, thereby, reduce processing time and provide a better specimen, is difficult to achieve. The transfer of heat from electrically heated hot plates or the like is extremely inefficient in a vacuum. Such heaters are therefore slow in this application and require considerable energy to operate.
One possibility is to use microwave energy to heat specimens in a vacuum centrifugal concentrator. Early attempts by the present inventor to use microwave energy showed that it was virtually impossible to attain meaningful heating rates at useful levels of vacuum due to the tendency for arcing under the electromagnetic field generated by the microwaves. Most of the energy is lost in arcing, thus preventing heating of the specimens, and also damaging the equipment.